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Biomedical subjects

A K Krey

Publications and source records attributed to A K Krey.

8 recordsLinked to original sources
PubMed1987

Morphogenesis and malformations of the skin NICHD/NIADDK research workshop.

Developmentally caused skin malformations constitute a spectrum of birth defects, some of which can be recognized prenatally by morphologic or biochemical means. The number of prenatally diagnosable skin diseases could be greatly expanded with an increased understanding of the molecular and cellular bases of skin development and the mechanisms that result in the generation of skin defects. The National Institute of Child Health and Human Development and the National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases, therefore, sponsored a workshop that recommended basic biologic studies combined with clinical investigations of normal and abnormal cutaneous development set forth in this article. Investigations resulting from these research recommendations are intended to contribute to the knowledge that should aid in the prevention of developmentally caused skin deformities.

APUD Cells↗
PubMed1975

Studies on the Methyl Green-DNA complex and its dissociation by drugs.

Spectrophotometric results indicated that Methyl Green bound stably to native calf thymus DNA and to poly[d(A-T)] but to a lesser extent to phiX 174 DNA, tRNAs, and poly(dG-dC), a copolymer that exists preferentially in the A conformation. Exposing the Methyl Green-DNA complex to graded concentrations of ethyl alcohol liberated part of the dye slowly by a zero-order reaction; higher alcohol concentrations which cause the B leads to A transition of DNA released the bulk of Methyl Green. The viscosity of the Methyl Green-DNA complex was significantly lower than that of the uncomplexed DNA. The dye was progressively liberated from DNA by 1.5 x 10(-1) M NaCl and by much lower concentrations of Mg2+; in its stoichiometric complex with DNA, it increased Tm by approximately 12 degrees C. A series of DNA-complexing drugs displaced Methyl Green from DNA at exponential rates and to end points which were correlated. End points of displacement correlated with the abilities of drugs to unwind supercoiled DNA, to labilize ribosomes to heat, and to eliminate a kanamycin resistance determinant from an R factor carried by Salmonella typhimurium. Additional correlations between Methyl Green displacement and biochemical-biological activities of displacing drugs are cited. In conjunction with these findings, our results suggest that Methyl Green displacement analysis is a useful biochemical screen for the detection or development of biologically active compounds which bind to DNA.

Animals↗
PubMed1975

Incorporation of double-labeled L-cystine and DL-valine in penicillin.

l-[3,3'-(3)H]cystine was incorporated into penicillin with retention of one tritium. This result can be explained by beta-lactam formation through ring closure between C3 of cysteine and NH of valine. No radioactivity of dl-[2,3-(3)H]valine was incorporated into penicillin. The loss of isotope at C2 occurs during the inversion of configuration. The loss of label at C3 is discussed in terms of possible intermediates for the formation of the thiazolidine ring of penicillin.

Carbon Radioisotopes↗
PubMed1969

Berberine: complex with DNA.

A complex of calf-thymus DNA with berberine sediments in the analytical ultracentrifuge. The DNA produced systematic changes in the absorption spectrum of berberine which suggest that single alkaloid molecules bind to DNA. Flow dichroism of purines and pyrimidines and of berberine in the complex with DNA had the same signs and magnitudes. Berberine shifted the thermal strand separation profile of DNA to higher temperatures. Therefore, the alkaloid forms a complex with DNA, probably by intercalation.

Animals↗